Multistage downhole anchor

ABSTRACT

The disclosure provides a downhole anchoring apparatus for use in a downhole tool. In an example implementation, a system is provided to anchor downhole tools in a wellbore. The system may include a tool body that fits within a wellbore casing, a slip having a wedge surface, a linkage connecting the slip to the tool body, and an actuator assembly. The actuator assembly may include a first actuator having a wedge surface corresponding to the slip wedge surface and a second actuator having a wedge surface corresponding to the slip wedge surface.

TECHNICAL FIELD

The embodiments disclosed herein relate generally to downhole tools for oil and gas wells, and, in particular to devices and methods for anchoring the tools in a wellbore casing section.

BACKGROUND

Downhole tools are often used to provide operations in oil and gas wells. Wirelines or slicklines are used to position downhole tools at a desired location in the wellbore. The desired location in the wellbore may be either cased or uncased, depending on the nature of the operation to be performed by the tool. In order to perform the desired operation, many wireline or slickline tools must be anchored in the wellbore to hold them in the correction wellbore location. This means the anchor must be able to resist not only unwanted movement of the tool in the axial direction, but also rotational movement caused by torque on the tool during the operation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a downhole anchoring system according to an embodiment;

FIG. 2 is a diagram illustrating a downhole anchor according to an embodiment with the slip retracted;

FIG. 3 is a diagram illustrating a downhole anchor according to an embodiment with the slip actuated by a first actuator;

FIG. 4 is a diagram illustrating a downhole anchor according to an embodiment with the slip actuated by a second actuator.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

As an initial matter, it will be appreciated that the development of an actual, real commercial application incorporating aspects of the disclosed embodiments will require many implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would nevertheless be a routine undertaking for those of skill in this art having the benefit of this disclosure.

It should also be understood that the embodiments disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Thus, the use of a singular term, such as, but not limited to, “a” and the like, is not intended as limiting of the number of items. Similarly, any relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like, used in the written description are for clarity in specific reference to the drawings and are not intended to limit the scope of the disclosure.

In one embodiment of the disclosure, there is provided a downhole anchor for anchoring a downhole tool in a desired section of the wellbore. FIG. 1 shows an anchoring system 100 according to an embodiment of the disclosure. Wellbore 102 of an oil and gas well is lined with casing 104. A wireline truck 106 may be used to deploy activation tool 108 at a desired location within wellbore 102 from wireline 110. An anchor according to an embodiment may also be deployed by a slickline or other method to position the anchor at a desired location in the wellbore. An activation tool can be any type of downhole tool that is activated downhole to perform a desired operation. Examples of actuation tools include any number of well intervention tools, such, as tools for setting packers, washing tools, milling tools, data gathering or sampling tools, and so forth. Generally, any downhole tool that requires anchoring may be used in embodiments of the system. Further, one or more anchors may be provided as necessary to maintain the activation tool in place. Similarly, in other embodiments, more than one activation tool may be included in the work string. For simplicity, in the embodiment depicted in FIG. 1, a single anchor 112 is provided to hold activation tool 108 in place. Anchor 112 includes radially extending slips 114 to engage the inner surface of wellbore casing 104 with sufficient force to hold activation tool 108 in place.

FIG. 2 is a diagram showing an anchor according to an embodiment of the disclosure. The anchor 112 includes a tool body or spine 116, a slip 114, and an actuator assembly 118 including a first actuator 120, and a second actuator 122. The slip 114 and actuator assembly 118 may be mounted, directly or indirectly, on tool body 116 and may move relative to it. In the embodiment shown, the second actuator 122 is housed inside the first actuator 120. The tool body 116 allows relative movement between the slip 114 and the first actuator 120 in an axial direction along the centerline 124 of the tool. An anchor 112 according to an implementation of the disclosure may include multiple slips and actuators arranged circumferentially around the tool body 116. The slips and actuators may also be arranged uniformly around the tool body 116 so that the anchor 112 self-centers when deployed in the wellbore. The tool body 116, including the slips and actuators, may also be housed in a housing that presents a smooth surface suitable for running down the wellbore without hanging or snagging. The slip 114 may be connected to the tool body 116 by slip holding linkage 126, which comprises a spring, such as a bow spring, to hold the slip 114 in position when not deployed. FIG. 2 depicts an implementation of the anchor 112 in the run-in-hole (RIH) arrangement, referred to as position 0 in the figure. The slip 114 and actuator assembly 118 components are contained within a downhole tool housing, not shown.

The slip holding linkage 126 allows the slip 114 to move radially outward from the centerline 124 when the anchor 112 is deployed. This linkage system also allows the slip 114 to move back to position 0 when the well operator decides to release the anchor 112 and re-position or remove it from the wellbore. The bow springs may assist in disengaging the slip 114 from the wellbore casing after deployment and moving back to position 0. The slips may be connected to the slip holding linkage 126 by a hinge to allow the casing engagement surface 128 to remain parallel to the centerline 124 as it is deployed and released.

The slip casing engagement surface 128 is suitable to engage the anchor 112 with the wellbore casing, and may have a textured surface, such as grooves or teeth, to help hold the anchor 112 in place without slipping when deployed. Securely holding the anchor 112 allows well operators to perform operations that require, for example, pushing against the anchor 112 for mechanical interventions in the wellbore.

The first actuator 120 may have a wedge profile, such as that shown in FIG. 2. The first actuator 120 includes a first wedge surface 130. The first wedge surface 130 is arranged at an angle less than ninety degrees relative to a normal to the centerline 124 of the tool. The amount of angle may be selected to determine the desired setting force required to deploy the anchor 112 in the wellbore. This allows multiple output forces within the same system. The first wedge surface 130 corresponds to a similar slip wedge surface 134 provided on the side of the slip 114.

To deploy the anchor, the first actuator 120 moves axially relative to the slip 114 in the direction of movement 132 shown in FIG. 2. Relative movement of the first actuator 120 toward the slip 114 causes the first wedge surface 130 to mate with the slip wedge surface 134. Continued movement causes the surfaces to slide relative to each other, forcing the slip 114 to move radially outward from the centerline 124. The radial movement of the slip 114 may continue until it reaches position 1, shown in FIG. 3.

As shown in FIG. 3, the slip 114 has moved a first radial distance R1, which is the furthest expansion obtainable by the relative movement between the slip 114 and the first actuator 120. The slip 114 may press against the slip support surface 136 of the first actuator 120. Also as shown, the second actuator 122 is now actuated. At position 1, the second actuator 122 is extended out from the first actuator 120 by, for example, internal wedges, linkages, or cams actin in tandem with the tool body 116 or housing. In the embodiment shown, the second actuator 122 is rotated out of the first actuator 120 on a hinge, though other actuation mechanisms may be used.

The second actuator 122 also may have a wedge profile and include a second wedge surface 138 that corresponds to the slip wedge surface 134. Additional relative movement between the actuator assembly 118 and the slip in the indicated direction of movement 132 causes the wedge surface 134 of the slip 114 to mate with the second wedge surface 138 and, subsequently, push the slip 114 outward from the first radial distance R1. This allows an anchor according to an embodiment of the disclosure to obtain a higher expansion ratio while maintaining the tool envelope than it would have with only the first actuator 120. Embodiments of the disclosure also allow the wedge angles of the slip and actuators to vary to determine the setting force and to allow a single setting movement. In other embodiments, the mating surfaces of the second wedge to slip could be made to have the same, or different, setting forces depending on the application.

FIG. 4 is a diagram showing an anchor 112 according to an embodiment at position 2, in which the second actuator 122 is fully actuated, and the slip has reached its maximum expansion radius R2. The slip 114 rests against second slip support surface 140 on the outer portion of the second actuator 122. At this point, the anchor would be fully deployed in the wellbore at its highest expansion ratio. This allows a multistage slip engagement, which may provide a wider range of setting than mechanisms having fixed expansion ratios, which may be limited by the actuator height and slope of the wedge surface. It may also allow embodiments of the anchor to latch onto a wide range of wellbore casing sizes while maintaining the envelope of the outer diameter (OD) of the tool and providing a larger engagement envelope.

After the wellbore operation is complete, the anchor 112 may be unlatched from the wellbore casing by moving the actuator assembly 118 axially away from the slip in the opposite of the direction of movement shown in the FIGS. 2-4. The bow springs, or similar mechanisms, cause the slip to retract radially toward the downhole tool centerline 124 until it reaches position 0, shown in FIG. 2. At this point, the anchor 112 may be repositioned or removed from the wellbore.

In one or more embodiments, a method is provided to anchor a downhole tool in a wellbore. The method may begin by providing an anchor having at least one slip and a multistage an actuator assembly, including a first and a second actuator contained in the first actuator, within a housing. The downhole tool may be initially arranged as shown in, for example, FIG. 2. The downhole tool may be then positioned in the wellbore at a desired location and the first actuator actuated by the relative axial movement of the slip with respect to the actuator assembly. The slip may be moved radially outward from the tool centerline by mating the wedge profiles of the slip and the first actuator until the slip reaches a first radial distance, such as shown in the example embodiment in FIG. 3. The relative motion of the slip toward the actuator assembly may also actuate the second actuator by causing the second actuator to move radially outward from the first actuator and present a second wedge surface to the slip. The slip may then be moved radially to a second radial distance by the relative movement of the slip and the actuator assembly, as shown in FIG. 4. When the anchor is to be detached from the wellbore casing, the slip may be moved away from the actuator assembly in the axial direction, reversing the steps above, until the anchor again reaches position 0, shown in FIG. 2. It may then be removed or repositioned in the wellbore.

In one or more embodiments, a downhole anchoring apparatus includes a slip having a wedge surface, a linkage connecting the slip to a first section of a tool body, a first actuator having a wedge surface corresponding to the slip wedge surface, and a second actuator having a wedge surface corresponding to the wedge surface of the slip.

In some embodiments, the downhole anchoring apparatus may further comprise any one of the following features individually or any two or more of these features in combination: (a) a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus, (b) a slip support surface located at a second radial distance from the centerline of the downhole anchoring apparatus, the second radial distance being less than or equal to the first radial distance when the second actuator is not actuated or engaged and being greater than the first radial distance when the second actuator is engaged, (c) a wedge angle that is different than a wedge angle of the second actuator wedge surface, (d) wherein the second actuator is positioned inside the first actuator when the second actuator is not engaged, (e) wherein the linkage comprises a spring, and (f) wherein the second actuator is engaged by the relative movement between the slip and the second actuator.

In one or more embodiments, a method for anchoring downhole comprises the steps of positioning a downhole tool in a wellbore, the downhole tool including a slip and a first actuator, and moving the slip along a centerline of the downhole tool toward the first actuator until a wedge surface of the slip mates with a wedge surface of the first actuator. Once the wedge surface of the slip is in contact with the wedge surface of the first actuator, moving the slip further along the centerline so that the wedge surface of the slip slides against the wedge surface of the first actuator, causing the slip to move radially outward from the centerline to a first expansion radius. The method may include actuating a second actuator having a wedge surface corresponding to the wedge surface of the slip, moving the slip further along the centerline and toward the second actuator until the wedge surface of the second actuator mates with the wedge surface of the slip. Once the wedge surface of the slip is in contact with the wedge surface of the second actuator, moving the slip further along the centerline, so that the wedge surface of the slip slides against the wedge surface of the second actuator, causing the slip to move radially outward from the centerline to a second expansion radius.

In some embodiments, the method may further comprise any one of the following features individually or any two or more of these features in combination: (a) wherein moving the slip further along the centerline and toward the second actuator until the wedge surface of the second actuator mates with the wedge surface of the slip further comprises moving the slip along a slip supporting surface of the first actuator, (b) wherein a wedge angle of the first actuator is different from a wedge angle of the second actuator to determine force control for setting the slip against a wellbore casing, (c) wherein actuating a second actuator further comprises moving the second actuator out of a location within the first actuator, and (e) wherein actuating a second actuator further comprises locking the second actuator in place once actuated.

In one or more embodiments, a system for anchoring downhole tools in a wellbore may include a tool body that fits within a wellbore casing, a slip having a wedge surface, a linkage connecting the slip to the tool body, a first actuator having a wedge surface corresponding to the slip wedge surface, and a second actuator having a wedge surface corresponding to the wedge surface of the slip.

In some embodiments, the system may further comprise any one of the following features individually or any two or more of these features in combination: (a) wherein the first actuator comprises a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus, (b) wherein the second actuator comprises a slip support surface located at a second radial distance from the centerline of the downhole anchoring apparatus, the second radial distance being less than or equal to the first radial distance when the second actuator is not engaged and being greater than the first radial distance when the second actuator is engaged, (c) wherein the wedge surface of the first actuator comprises a wedge angle that is different than a wedge angle of the second actuator wedge surface, (d) wherein the second actuator is positioned inside the first actuator when the second actuator is not engaged, (e) wherein the linkage comprises a spring, (f) wherein the second actuator is engaged by the relative movement between the slip and the second actuator, and (g) wherein the first actuator comprises a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus.

While the disclosed embodiments have been described with reference to one or more particular implementations, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the description. Accordingly, each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the following claims. 

What is claimed is:
 1. A downhole anchoring apparatus comprising: a tool body; a slip having a wedge surface; a linkage connecting the slip to a first section of a tool body; a first actuator having a wedge surface corresponding to the slip wedge surface; and a second actuator having a wedge surface corresponding to the slip wedge surface.
 2. A downhole anchoring apparatus as in claim 1, wherein the first actuator comprises a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus.
 3. A downhole anchoring apparatus as in claim 2, wherein the second actuator comprises a slip support surface located at a second radial distance from the centerline of the downhole anchoring apparatus, the second radial distance being greater than the first radial distance when the second actuator is actuated.
 4. A downhole anchoring apparatus as in claim 2, wherein the wedge surface of the first actuator comprises a wedge angle that is different than a wedge angle of the second actuator wedge surface.
 5. A downhole anchoring apparatus as in claim 1, wherein the second actuator is positioned inside the first actuator when the second actuator is not actuated.
 6. A downhole anchoring apparatus as in claim 1, wherein the linkage comprises a spring.
 7. A downhole anchoring apparatus as in claim 1, wherein the second actuator is actuated by the relative movement between the slip and the first actuator or relative movement between either the slip or the first actuator with respect to the tool body.
 8. A method for anchoring downhole tools, the method comprising: positioning a downhole tool in a wellbore, the downhole tool including a slip and a first actuator; moving the slip along a centerline of the downhole tool toward the first actuator until a wedge surface of the slip mates with a wedge surface of the first actuator; when the wedge surface of the slip is in contact with the wedge surface of the first actuator, moving the slip further along the centerline so that the wedge surface of the slip slides against the wedge surface of the first actuator, causing the slip to move radially outward from the centerline to a first expansion radius; actuating a second actuator having a wedge surface corresponding to the wedge surface of the slip; moving the slip further along the centerline and toward the second actuator until the wedge surface of the second actuator mates with the wedge surface of the slip; when the wedge surface of the slip is in contact with the wedge surface of the second actuator, moving the slip further along the centerline, so that the wedge surface of the slip slides against the wedge surface of the second actuator, causing the slip to move radially outward from the centerline to a second expansion radius.
 9. A method as in claim 8, wherein moving the slip further along the centerline and toward the second actuator until the wedge surface of the second actuator mates with the wedge surface of the slip further comprises moving the slip along a slip supporting surface of the first actuator.
 10. A method as in claim 8, further comprising controlling the force to set the slip in the casing using a difference between the wedge angle of the first actuator and the wedge angle of the second actuator, allowing multiple setting forces in the same downhole tool.
 11. A method as in claim 8, wherein actuating a second actuator further comprises moving the second actuator out of a location within the first actuator.
 12. A method as in claim 8, wherein actuating a second actuator further comprises locking the second actuator in place once actuated.
 13. A system for anchoring downhole tools in a wellbore, the system comprising: a tool body that fits within a wellbore casing; a slip having a wedge surface; a linkage connecting the slip to the tool body; and an actuator assembly including a first actuator having a wedge surface corresponding to the slip wedge surface and a second actuator having a wedge surface corresponding to the slip wedge surface.
 14. A system as in claim 13, wherein the first actuator comprises a slip support surface located at a first radial distance from a centerline of the downhole anchoring apparatus.
 15. A system as in claim 14, wherein the second actuator comprises a slip support surface located at a second radial distance from the centerline of the downhole anchoring apparatus, the second radial distance being greater than the first radial distance when the second actuator is actuated.
 16. A system as in claim 14, wherein the wedge surface of the first actuator comprises a wedge angle that is different than a wedge angle of the second actuator wedge surface.
 17. A system as in claim 13, wherein the second actuator is positioned inside the first actuator when the second actuator is not actuated.
 18. A system as in claim 13, wherein the linkage comprises a spring.
 19. A system as in claim 13, wherein the second actuator is actuated by the relative movement between the slip and the actuator assembly or relative movement between either the slip or the actuator assembly relative to the tool body.
 20. A system as in claim 13, wherein both the second actuator comprises a locking mechanism to hold it in place when actuated by the movement of the slip axially toward the actuator assembly. 